Infrared signaling has many applications. A common application is in the field of aviation. The infrared signal can be detected by aircraft in the weather conditions where visible light cannot readily be detected. Traditional incandescent bulbs (colored as needed) convert 95% of the supplied energy to heat, thus producing infrared energy. Hence, as new sensing technologies have been developed infrared imagers have been placed in the cockpits of airplanes. The infrared imagers assist pilots to see images of the runway landing area in inclement weather, increasing safety. The United States Federal Aviation Administration has therefore promulgated rules for aircraft approach lights which include infrared signaling.
The advent of LED lights, which can be 95% efficient or more, has reduced the infrared signal that can be detected. There is little heat generated by LEDs which can be detected by the infrared imagers on the planes. These imagers primarily view in the 760 nm to 2000 nm wavelengths, and hence, an added method to generate IR signals in these wavelengths is needed.
Carbon foams are known to have many desirable properties. These properties include high thermal conductivity, and a very high specific thermal conductivity which can be 4 times that of copper. Examples of such foams and of methods to prepare such foams can be found in U.S. Pat. No. 6,033,506, U.S. Pat. No. 6,261,485, U.S. Pat. No. 6,387,343, and U.S. Pat. No. 6,673,328, the disclosures of which are hereby incorporated fully by reference.